MITOCHONDRIAL-DNA, ALLOZYMES, MORPHOLOGY, AND HYBRID COMPATIBILITY INLIMNOPORUS WATER STRIDERS (HETEROPTERA, GERRIDAE) - DO THEY ALL TRACKSPECIES PHYLOGENIES

The six extant species of Limnoporus water striders provide an unusual opportunity to compare allozyme and mitochondrial DNA (mtDNA) diverge nces with both morphological divergences and information on interspeci fic hybrid inviability. Parsimony analyses of mtDNA, allozymes, and mo rphology did not differ greatly, and each data type provided useful in formation on at least some nodes in the phylogeny. Simultaneous analys is of the combined data gave a better resolved and supported tree than did any single data type. Several measures of hybrid inviability bore no relationship to genetic distances between species, thus demonstrat ing the poor value of hybrid compatibility as an indicator of phylogen etic relationships. When genetic distances were related to estimates o f time of divergence based on fossils, standard molecular clocks for m tDNA and allozymes showed as much as a 10-fold underestimate of absolu te time. The phylogeny of Limnoporus allows more rigorous evaluation o f several prior hypotheses of ecological or developmental processes in water striders. In particular, the phylogeny supports the evolutionar y lability of wing dimorphism, sexual size dimorphism, and local diffe rentiation of ontogenetic traits.